I wanted a way to be able to determine roughly how long it had been since a user had been active. I defined active to mean that the user had had to authenticate onto a system. This is so that a box on which the user had logged in has gone into screen lock, and the user has then authenticated again to the display manager.
I used the audit log of auditd to detect when a user has authenticated to a display manager. Auditd comes installed on Fedora, but I had to install it on the ubuntu boxes. Continue reading Recording last authentication